The invention relates to scintillation crystals. More particularly, the invention relates to scintillation crystals of the type which are used in radiation dose monitoring programs. In its most immediate sense, the invention relates to thermoluminescent dosimeter (TLD) crystals.
In work places where employees are subjected to ionizing radiation, the total dose of radiation to which the employee is subjected must be monitored. This permits the empolyer to ensure (by appropriate reassignments) that no employee receives more than a predetermined maximum dose of radiation in a particular period.
To do this, it is known to use a radiation badge which is given to, and worn by, the employee. The badge contains a TLD crystal. During use, ionizing radiation strikes the crystal and creates trapped electrons. When the crystal is then heated up, scintillation events are created in proportion to the amount of radiation to which the crystal has been exposed, and the scintillation events are counted to register this radiation exposure. After the crystal has been read out, it is annealed to remove all the trapped electrons, and is then reused.
In a conventional radiation monitoring program, an employer issues each of its employees a radiation badge at, for example, the beginning of the week. The employee wears the badge for the week and takes it off, and all the badges are then sent to a service organization. This organization processes the badges, reads out and organizes the radiation dose information for the various employees, and restocks the badges with annealed crystals for reuse during the next week.
The handling of the scintillation crystals presents difficulties for the service organization. Because the crystals are small and bear no identifying marks, they must be, e.g., manually placed in a magazine of some sort in a known order. This is because the crystals vary in their response to ionizing radiation and the scintillation data generated during readout can be properly interpreted only if the response of the crystal is taken into account. Furthermore, even after the crystal has been read out and annealed, the crystal must continue to be identifiable because it is reused.
Various attempts have been made to affix identifying marks to the scintillation crystals. These include printing, labelling, etc., but for one reason or another, all have proved unfeasible.
It would be advantageous to eliminate mechanical difficulties associated with handling of scintillation crystals, particulary crystals such as are used in radiation badges.
One object of the invention is to provide a technique by which a scintillation crystal, particularly of the type used in radiation badges, can be physically identified.
Another object is to generally facilitate the processing of radiation badges.
Still another object is to generally improve on known devices and methods used in processing of radiation badges.